1. Field of the Invention
This invention relates to an actuator and a roller equipped with at least one such actuator for a web-processing machine. In this case said machine can be in particular a machine for producing a fibrous web, in particular a paper web, paperboard web or tissue web.
2. Description of the Related Art
Many different mechanisms made of levers, spindles or adjustable screwed connections are known for the linear height adjustment of components such as bearings. A disadvantage of said known adjustment devices or actuators is that the adjustment is very complicated because clampings have to be released and/or components cannot be connected to each other rigidly enough and therefore work or vibrate.
In the interest of a rigid, low-vibration connection use has already been made therefore of eccentric bearings because they enable a direct, rigid bearing arrangement for components for example on an eccentric shaft, such bearing arrangement being connected directly to the component in question without joints via a sliding bearing arrangement.
However, a simple eccentric is accompanied by the disadvantage that an adjustment in one plane simultaneously entails a change in a second plane because such a simple eccentric always includes a displacement in a corresponding angular position.
On a roller with adjustable bending known from DE 199 27 897 A, setscrews are provided for the variable setting of the bend.
To guide the web on web-processing machines, provision has been made up to now for arrangements on which in particular guide rollers, regulation rollers and expander rollers are arranged in succession. A disadvantage of these known arrangements are, among other things, their high investment and maintenance costs.
Because of the simple construction of a guide roller, its components are extremely economical. However, it is a disadvantage that the web run can be negatively influenced through compliance of the guide roller.
Expander rollers are used in web-processing machines in order to prevent fold formation or sagging on a running material web by expanding the material web. Also, expander rollers are used to guide apart material webs that are arranged side by side and parallel with each other. Material webs arranged side by side and parallel with each other can be produced by slitting a wide material web for example. Such expander rollers are known for example from DE 199 27 897 A1 and DE 10 2004 045 407 A1.
Expander rollers often include several individually mounted segments which entail a high level of maintenance and are accordingly cost-intensive. The maintenance of such an expander roller generally costs approximately 60% of the new price. Furthermore, the usual expander rollers used hitherto have a very slim construction and an accordingly low load-carrying capacity so that their use as a guide roller is ruled out.
The newest expander roller versions based on high-performance plastics have optimized curvatures. The disadvantage of said versions is however that the constructions in question are not torque-free mounted, meaning that the support of the machine in question, for example a paper machine, is loaded in undesirable manner. In the case of new plants, account must be given to the torques arising, which requires cost-intensive reinforcements. In the case of existing plants, even more expensive auxiliary structures are required.
What is needed in the art is an improved actuator of the type initially referred to, which enables on the one hand a linear adjustment and on the other hand an adjustment of the angular position of the adjustment. In this case said actuator should be suitable in particular as a control mechanism for a rigid, adjustable bearing arrangement. It is thought to use said actuator in particular on a roller for a web-processing machine. In addition it is intended to create an improved roller of the type initially referred to, with which the previously mentioned problems are eliminated. In particular the torques introduced into the support should also be minimized. Finally, the roller in question should also be suitable for performing the functions of several different roller types simultaneously.